JPS60239596A - Production of pigment coated paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing coated paper having novel properties.

[Technical background]

Round pigment-coated paper, which is coated with a water-based paint containing pigments, adhesives, and small amounts of other additives on the surface of the paper base, is classified into art paper, coated paper, cast coated paper, etc., depending on its manufacturing method and properties. Most of the paper is used as high-quality printing paper for pamphlets, calendar paper, book (including magazine) paper, packaging paper, and paper carton material.

On the other hand, in many cases, these pigment-coated papers are made into products by being smoothed using heating and pressure mechanisms, such as finishing equipment called super calendars, machine calendars, and thermal calendars. For convenience, it is classified according to the gloss level (ratio of 75' incident luminous flux to 75° reflected luminous flux) of the surface of the coated layer after finishing treatment. For example, gloss of 55% or higher is cross-like coated paper, and 40 to 55% is mid-gloss coated paper. Covering paper, 20~
40 inch paper is called dull coated paper, and 20 inch or less paper is called matte coated paper, etc., and can be used depending on the customer's preference.

Naturally, the pigment-coated paper used as a printing medium in the above-mentioned printing process is one that has both workability during printing and print surface quality after printing, that is, sufficient printability. However, in recent years, market demands, especially regarding printing quality, have become more sophisticated and diversified.

[Purpose of the invention]

An object of the present invention is to provide coated paper with new functions in order to meet the high quality demands of the market. In other words, the glossiness of the formed coating layer (hereinafter abbreviated as white paper glossiness) is at a low level, such as matztrudal or midgloss, but the glossiness of the printed surface after printing (hereinafter abbreviated as printing glossiness) is at a low level. To provide a coated paper which is of a high standard comparable to that of cloth-like coated paper, and which produces printed matter with high contrast between a non-image area with low white paper gloss and an image area with high print gloss and high resolution. It is in.

[Structure of the invention]

The present invention uses a paint having a surface gloss level of 50% or more and containing at least 40 weight of calcium carbonate pigment with a cL of 1 to 1.0 μm based on the total pigments in the paint, in an absolute dry weight ratio of 5 f/- or more. The surface of the coating film formed by single-stage coating of pigment-coated paper or the final coating layer formed by multi-stage coating is modified with an acid or an acidic or neutral salt. This is a method for producing pigment-coated paper, which is characterized by:

Conventionally, many efforts have been made to meet the increasingly sophisticated quality requirements for pigment-coated papers on the market.

For example, JP 59-9680, JP 59-4319
As seen in 3, the imparting of functionality to the constituent materials of paint for the formation of coating layers, Special Publication No. 59-3597, Special Publication No. 59-3
Many efforts are still being made, such as those related to the paint composition conditions to achieve a glossy finish such as 598. However, in order to satisfy the relationship between the glossiness of white paper and the glossiness of printing, which is the aim of the present invention, which may seem contradictory, it is not possible to achieve this only by applying these methods, and it is necessary to come up with an innovative idea. It is necessary to take stock. In fact, the inventors have so far developed several dozen commercially available coated papers in a wide range of white paper glossiness, from matte-coated paper to cross-coated paper, and even cast-coated paper that can be called supercross-like. As a result of evaluating the printing glossiness of the paper, the white paper glossiness and the printing glossiness were highly correlated with each other, and the coated paper that could achieve the desired low white paper glossiness - high printing glossiness, or a coated paper similar to this, was found to be I couldn't find a single one. Therefore, in order to break the balance between white paper gloss and printing gloss, the inventors investigated the individual factors that influence each, namely, the ultramicroscopic roughness of the coating layer surface with a width of 00 to 10 μm, and the microscopic roughness with a width of 10 to 100 μm. Visual roughness, 100
The causal relationship between macroscopic roughness expressed as roughness of μm or more, physical properties such as pore size, distribution, and microscopic interface state of the surface layer, and chemical properties such as lipophilicity and hydrophilicity. was considered in detail. They have also discovered that white paper gloss and print gloss are not necessarily influenced by the same factors, and that there is a possibility that the balance between the two may be disrupted.

Therefore, we assume several coating films that are estimated to be capable of exhibiting low white paper glossiness and high print glossiness.
A microscopic roughness of about 0 to 100 pm in width is maintained, and a microscopic roughness of 10 μm or less in width is maintained to suppress excessive penetration of ink components into the coated layer and to improve retention and continuity of the ink film. The present invention was arrived at as a result of extensive research and study on a method for forming a coating layer that can reduce microscopic roughness.

The method of the present invention achieves the object by secondarily performing a chemical modification treatment on the surface of the coated layer once formed as described in the claims. The base paper before modification treatment used in the method of the present invention may be coated in a single stage or in multiple stages, but the coating amount of the final coated layer in a single stage coating layer or multi-stage coating is at least 5 f bone dry weight
/- or more, and generally the total pigment of coated paper for printing accounts for 70 to 80 inches (weight ratio) of the total solid content in the paint, but this total pigment contains particles with a particle size of α1 to μm (preferably α2 to α7
40-100% by weight (μm) of calcium carbonate pigment (
(preferably 60 to 80 inches). Further, after the coating layer is formed, this base paper must be given smoothness with a gloss level of 55 inches or more using a finishing equipment such as a super calender. If the final coating layer in a single-stage coating layer or multi-stage coating is less than 517 m, the internal penetration of the modifying liquid will be significant and will likely cause non-uniformity of the modified coating layer. Calcium carbonate highly reactive with the reforming liquid, i.e. particle size α1-1
．． When calcium carbonate of 0 μm is 40 dw,
It becomes difficult to lower the white paper glossiness to the desired level after the modification treatment. Furthermore, even when the particle size of calcium carbonate is smaller than the above range, it is difficult to reduce the white paper gloss. If the smoothness of the pigment-coated paper (pigment-coated paper) does not reach the above level, the surface of the coated layer after modification will have an excessively rough structure, and the continuity of the ink film after printing will deteriorate. As a result, high printing gloss cannot be obtained. In the present invention, there are no restrictions on the composition of the base paper, the components of the coating layer other than the pigment, the coating method, etc.

On the other hand, as a modification liquid, zinc sulfate, aluminum sulfate,
Acids or acids that are reactive with calcium carbonate, such as formic acid, calcium formate, sodium formate, calcium acetate, etc.
Although an aqueous solution of a neutral salt can be used, strong acids such as hydrochloric acid and sulfuric acid are not preferred from the viewpoint of adverse effects on the strength of the coating layer and the working environment. Moreover, ammonium salts of the above acids can also be used. Furthermore, by changing the concentration of the aqueous solution, the white paper glossiness can be set to an arbitrary level, but the concentration level differs depending on each treatment liquid. The acids and salts used in the method of the present invention fill up the microscopic pores of 10 μm or less on the surface of the coating layer, suppress internal penetration of ink components, and maintain good coverage of the ink film. Ink transfer, dampening water transfer, etc. in offset printing etc. tend to be somewhat lower than in the coated layer before treatment. but,
These coated papers are of a level comparable to that of commercially available coated papers and are well suited for reed printing, offset printing, and the like.

There are several methods for surface modification, such as immersing the coated layer in a modifying solution and scraping off excess modifying fluid with a rond or air knife after application. I don't mind.

On the surface of the coating layer modified by the above treatment liquid, excessive salt or fine powder, which is presumed to be a reaction product with the treatment liquid components, may adhere and easily detach. . Therefore, in order to prevent such a phenomenon, it is preferable to incorporate a suitable amount of a substance having a binder effect. As the binder, synthetic binders such as starch, polyvinyl alcohol, and polyacrylamide can be used, but when salt is used as a modifying liquid component, nonionic-cationic substances that do not impair the activity of the salt's cations can be used. It is necessary to select

The purpose of the present invention can be achieved by satisfying the above requirements, but there is a need for countermeasures when bubbles occur during operation, or when it is desired to provide a coloring function during reforming. In some cases, various chemicals can be added to the modification liquid, but in this case as well, it is preferable to select the chemicals to be added from nonionic to cationic substances.

Next, the present invention will be explained with reference to Examples, but the present invention is not limited by the Examples.

Example-1 20 t/m of paint having the following composition was applied to the felt surface of Z base paper with a basis weight of 80 g/m using a blade coater.
(absolute dry weight) A base paper was prepared by applying a coating and smoothing treatment using a super calender, and finishing the coated surface with a gloss level of 65.

Paint composition: First grade kaolinite clay...30 parts Oxidized modified starch...3 parts Styrene, butadiene latex...20 parts Polyoxycarboxylate...3 parts Epoxy resin ...... One part of the above coated paper containing 1.5, 2.0 and 50% aluminum sulfate (as A &(SOn'h18HzO)) and a quarter of each polyvinyl alcohol. 35f/
As shown in Table 1, as shown in Table 1, the glossiness of mid-gloss, dull and matte coated paper (corresponding to white paper) was obtained under each condition. YoJ (L35wd Toyo Ink 5UPERAP
As a result of printing with EXNK (red) 5c, high printing gloss comparable to commercially available art paper was obtained. We also evaluated the coated surface strength, dampening water resistance, ink receptivity, multicolor offset printing test, and other properties for printing, and all of them were found to be at the same level as commercially available coated paper, sufficient for offset printing. It was shown that it is compatible with

Table 1 Comparative Example-1 The same base paper as in Example-1 was not subjected to finishing treatment, or after being smoothed with a super calender under conditions where the gloss level was 50% or less, the paper was treated under the same conditions as in Example-1. As a result of the modification treatment, as shown in Table 2, the glossiness of the white paper decreased as the concentration of the modification solution increased, but the glossiness of the print also decreased at the same time, making it impossible to obtain the desired coated paper.

Table 2 Comparative Example-2 When treated in exactly the same manner as in Example-1 with the only difference being the paint composition of the base paper, as shown in Table 3, the decrease in white paper gloss was very small. Although this can be lowered by increasing the concentration of the liquid, the print gloss also decreases at the same time, making it impossible to obtain the desired coated paper.

Coating composition: First grade kaolinite clay... 75 parts 0 The rest is the same as Example-1 Table 6 Example-2 The surface of the base paper similar to Example-1 was coated with 15.20 and 25% formic acid aqueous solution. As shown in Table 4, when treated as a modifying liquid, a white paper gloss equivalent to that of mid-gloss, dull and matte coated paper was obtained, and the printing gloss was also at a high level comparable to commercially available art paper.

In addition, other printing properties such as coated surface strength, dampening water resistance, and ink receptivity were also good, and the material was sufficiently suitable for offset printing.

Table 4 Example-3 Secondary kaolinite clay on the felt surface of the same base paper as in Example-1 40 parts -grade kaolinite clay 25 parts oxidized modified starch 5 parts styrene butadiene latex ・-18 parts sodium polyphosphate ・・・ 2 parts epoxy resin ・・・ Coat the paint consisting of 1 part with a blade coater.
(absolutely dry weight) was applied with an undercoat, and then the paint of Example-1 was applied with a metering rod at 10f/渭3 (absolutely dry coating weight), and the same operation as in the example was performed. .

As a result, as shown in Table 5), white paper gloss levels corresponding to mid-gloss, dull and matte coated papers were obtained,
The printing gloss was also at a high level comparable to commercially available art paper. In addition, the printability of coated surface strength, dampening water resistance, ink receptivity, etc. was also evaluated, and all were at the same level as commercially available coated paper, indicating that it is fully suitable for offset printing.

Table 5 Example-4 The surface properties of the base paper obtained in Example-1 were changed to a glossiness value in the range of about 30 to 80 inches by supercalendering.
．． A modification treatment was carried out using a modification solution containing aluminum sulfate at a concentration of 5% and polyvinyl alcohol at a quarter of this amount. As a result, regardless of the glossiness of the base paper as shown in Table 6, the desired level of white paper glossiness can be obtained, but the desired high printing glossiness can be achieved when the glossiness of the base paper is 5%. Only the conditions listed above were obtained.

Table 6 Example-5 Additives other than pigments were added to the surface of the base paper in Example-1 under the same conditions as above, but the pigment composition was primary kaolinite clay/
The calcium carbonate ratio was varied from 0/100 to 10010, and the coating was applied to give an absolute dry weight of 2097 m'', and then finished to a gloss level of 60% using a super calender, and the same treatment as in Example 4 was performed. .

As a result, it was possible to reduce the white paper gloss to the desired dull tone only under the conditions shown in Table 7, where calcium carbonate accounted for 4 parts or more of the total pigment.

Table 7 In addition to the above examples, the inventors have also
Experiments were also conducted on the particle size ring of calcium carbonate in the base paper coating. When the coated amount of the base paper was less than 5 f/m'' (absolute dry weight), the surface of the modified coating film became extremely uneven and was not worth evaluating. The particle size of the calcium pigment falls within the claimed range (α1 to 1
．． When the diameter is smaller than 0 μm), the coating film on the base paper becomes extremely dense, the reactivity with the modifying liquid deteriorates, and the white paper gloss cannot be lowered to the desired level. On the other hand, if a coarser calcium carbonate is used, extremely high gloss will not be developed during the stage of smoothing the base paper. As above, the porosity of the base paper coating was lost and the reaction with the modifying liquid was insufficient.

Patent Applicant Oji Paper Co., Ltd. Agent Hirodo Nakamoto Shodo Inoue Katsune Yoshimine Amendment (spontaneous) June 26, 1980 Commissioner of the Patent Office Manabu Shiga 1, Indication of the case 1988 Patent Application No. 94621 2,
Title of the invention Relationship to the case of the person making the five amendments to the method for producing pigment-coated paper Patent applicant address 4-7-5 Ginza, Chuo-ku, Tokyo Name Name Oji Paper Co., Ltd. Representative Umigame 2nd Department & Amendment Claims column and Detailed Description of the Invention column of the subject specification Contents of amendment (1) The claims are amended as shown in the attached sheet.

(2) “For all pigments [lL1~
1.0μ of ” to ”average particle size α1 to 1.0 for all pigments”
Corrected as "μm".

(3) "Particle size" on page 6, line 14 is corrected to "average particle size."

λ Patent Claim 1: It has a surface property with a gloss level of 50% or more, and has an average particle size of 0.1 to 1.5% with respect to all the pigments in the paint. Paint containing 40% by weight or more of OIIm calcium carbonate pigment at an absolute dry weight of 5f/
The surface of the coating film formed by single-stage coating or the final coating layer formed by multi-stage coating of pigment-coated paper coated at a ratio of m2 or more is treated with an acid or an acidic or neutral salt. A method for producing pigment-coated paper, which comprises modifying the paper.

Claims (1)

[Claims] 1. Calcium carbonate pigment 40, which has a surface gloss of 50% or more and has a cL of 1 to 1.0 μm based on the total pigment in the paint.
Multi-layered coating film formed by single-stage coating or multi-layered coating formed by multi-stage coating of pigment-coated paper trap-coated with a paint containing % by weight or more at a ratio of 5 g/m'' (bone dry weight) or more A method for producing pigment-coated paper, which comprises modifying the surface of the final coated layer with an acid or an acidic or neutral salt.